Stab-in conduit couplings



United States Patent 3,456,729 STAB-IN CONDUIT COUPLINGS James M. Harwell, In, Houston, Tex., assignor to Gray Tool Company, Houston, Tex., a corporation of Texas Continuation of application Ser. No. 553,224, May 26, 1966. This application July 25, 1968, Ser. No. 751,007 Int. Cl. E21b 19/00; F161 21/00 U.S. Cl. 166226 8 Claims ABSTRACT OF THE DISCLOSURE A tieback sub is described for stabbing into a tieback collar for instance on a remotely located casing hanger. The collar is internally threaded to accommodate attachment of well components. Above the internal threading a plurality of longitudinal slits through the collar are spaced angularly from one another. Teeth are formed in the bore of the collar between the ends of these slits. The tieback sub is provided with external elements cooperable with the teeth to connect the sub to the collar. There are also cooperative stops provided on the sub and collar to limit incursion of the sub into the bore of the collar.

This application is a continuation of copending application, Ser. No. 553,224, filed May 26, 1966, and now abandoned.

The present invention relates to stab-in conduit couplings particularly useful for tying back into sub-sea temporarily abandoned petroleum wells.

In the commonly assigned, copending U.S. patent application of Pitts et al., Ser. No. 539,242, filed Feb. 18, 1966, and now Patent No. 3,405,763, a development relating to hanging casing in sub-sea wells near the mudline so that particular wells can be temporarily abandoned upon substantial completion, during the time that nearby formtaion definition wells are being drilled to determine if there is a sufficient amount of recoverable petroleum in the area to warrant installation of production, collection, temporary storage and/or other similar equipment necessary to produce from the wells. One important feature of the development disclosed therein is means for separating all of the conduit risers from their respective casing strings just above the near-the-mud-line hangers so that a temporary abandonment cap can be placed on the well so near the mud-line that the temporarily abandoned well is not a hazard to navigation.

The exemplary separating means shown in that application comprise coarse cooperative threading, for instance, two pitch acme threads, adjacent the ends of the parts to be separated.

Although the development just described has proved to be very successful in facilitating completion, temporary abandonment and tying back into temporarily abandoned wells, the present invention grew out of anticipation that between separation of risers from mud-line suspended casing strings to eifect temporary abandonment and tying back into such wells, the threading on the upper ends of the sub-sea parts could become so damaged that a threaded reconnection could be made.

Accordingly, a major object of the present invention is the provision of means for tying back into remote conduits such as mud-line suspended casing strings, sub-sea casing hanger housings and the like, which do not require relative rotation between the parts to be connected in order to form a sealed connection, even it previously used threading has become severely damaged.

A further object of the present invention is the provision of apparatus of the type described which is susceptible of reseparation by relative rotation of the connected parts.

'ice

Recognizing that the invention has broader applicability than to solution of the specific problem just outlined, it is an object of the present invention to provide an improved stab-in joint for conduits or other parts such as pressure vessel-pressure vessel closure arrangements, rod to socket couplings and the like.

These and further objects of the present invention as well as the principles and scope of applicability of the invention will become more clearly apparent during the following detailed discussion relating to the exemplary embodiments depicted in the attached drawings.

In the drawings:

FIGURE 1 is a side elevation view with parts broken away of a sub-sea casing hanger body having a stab coupling provision according to the present invention, and a lowering sub and riser threadably engaged with the casing hanger body;

FIGURE 2 is a fragmentary side elevation view similar to the rightmost region of FIGURE 1 showing a succeeding completion stage wherein the landing sub has been threadably backed out of seated condition by about four turns in order to expose circulation ports for cementing; and

FIGURE 3 is a fragmentary side elevation view of a subsequent completion stage wherein the landing sub has been replaced by a stabbed-in tieback sub according to the present invention.

The sub-sea well 10 of FIGURE 1 includes an outer casing (not shown) driven to refusal in the sub-sea earth. The outer casing has a hanger support seat formed in its bore about 20 feet below the mud-line 12. An inner casing string 14 is shown being lowered into the well by a landing sub 16 for suspension via a hanger 18 from the outer casing support seat, the hanger 18, being provided with an external circumferential downwardly facing shoulder for this purpose. The beginning of the enlargement on which the shoulder is formed is indicated at 19; the shoulder itself is below the lower extent of FIGURE 1, its correspondents being numbered 14 and 22 in FIGURE 1 of the commonly assigned copending application of Quebe and Grain, Ser. No. 553,245, filed May 26, 1966, and now Patent No. 3,400,950.

Several, for instance thousands of feet of easing are secured by conventional means to and depend from, the lower end of the hanger 18.

The landing sub 16 is generally tubular and has means such as internal threading 20 at the upper end of its bore 22 by which it is secured to a pipe or casing riser 24 via exterior threads 26. The riser 24 extends to the sea surface where the lowering of the casing string 14 is initiated and guided from a ship or platform mounted rig.

Starting upwardly from the enlargement 19, the hanger 18 is shown having a plurality of angularly spaced, radially directed circulation ports 28 which communicate with the hanger 18 bore 30 a few feet above the enlargement 19, and having a plurality, for instance twenty-four, angularly spaced narrow, vertically elongated slits 32 which proceed through the wall of the hanger 18 and communicate with the bore 30 thereof. The hanger 18 upper end 34 is preferably at or near the mud-line when the casing string 14 is landed.

Proceeding upwardly from the shoulder 36, the bore 30 can be seen to be first cylindrically curved at 38, then frustoconically enlarging to provide a sealing surface 40, next cylindrically curved at 42, then threaded at 44, with for instance, two-pitch Acme threads.

Above the threads 44, the bore 30 is cylindrically curved at 46 coincident with the root of the threading 44 up to 48 and an upwardly facing annular circumferential shoulder formed where material has been removed to form circumferential spiralled teeth 50 extending over the central approximately half of the area delimited by the upper and lower extent of the flutes or slits 32. Each tooth 50 includes a generally radially projecting, downwardly facing lower surface 52 and a generally flaring, upwardly facing, upwardly enlarging side surface 54. The teeth are preferably hardened for instance by cold working, by flame hardening, case hardening or the like (q.v. Metals Handbook, ASME, Cleveland, Ohio (1948), pp. 647-651, 677-702). Such processes harden the teeth, but leave the bulk of the ribs 55 defined between the slits 32 relatively elastically de flectable. It should be clear that the single, multitple turn spiraling at 50 is divided into discrete teeth by the slits 32.

The landing sub 16 is received within the hanger bore 30 and removably secured as shown in FIGURE 1, by threading 56, such as two pitch Acme threads engaged with the hanger threads 44. The former are not so axially extensive as the latter so that the sub 16 can be threadably advanced and Withdrawn at least a few turns without disengaging any of its threads 56 from a like number of threads 44. This should be seen to be an advantage in insuring that withdrawing the sub a few turns does not increase the supporting load that must be carried per thread. Adjacent its lower end 58, the lowering sub is provided with a downwardly and outwardly facing, tapered annular sealing surface 60 having circumferential radially outwardly opening recesses 62 in which hydraulic packing material 64 is received. In FIGURE 1, the surfaces 60 and 40 are in coextensive engagement with the packing 64 forming a stressed seal between the sub 16 and the hanger 18. Upwardly from the surface 60, the sub is cylindrically curved at 66 complementarily to the hanger bore surface 42. Two axially spaced, radially outwardly opening annular grooves 68 are formed in the surface 66 and receive hydraulic packing 70, or the like to form circumferential seals above and below the circulation ports 28 when the parts 16, 18 are in their FIG- URE 1 relative positions. Spaced above the threads 56, the landing sub 16 exterior is provided with a cylindrical surface 72 complementary to the surface 46 and includes annular grooves 74 provided with packing material 76 for sealing with the surface 46 to protect the threads 44, 56. The landing sub 16 could be provided with an en larged shoulder at 76 for engagement with the hanger 18 upper end to limit advancement of the landing sub into the hanger bore to the extent shown in FIGURE 1.

When the casing string 14 has been landed within the outer casing the annulus between the two is cemented as more fully discussed in the above-mentioned copending application of Pitts et al., by circulating cement down the bore of the string 14 and up to the surface in the intercasing annulus, then threadably backing the landing sub 16 out of the hanger bore 30 by about four turns to expose the ports 28 (FIGURE 2) and circulating fluid down the bore of the string 18, out the ports 28 and up the intercasing annulus to the surface. This process ensures that the casing string 14 is securely cemented in place but that the joint between the landing sub 16 and easing hanger 18 is free of cement. At this point the well can be further completed for instance as described in the above-mentioned application of Pitts et al. and temporarily abandoned at a later stage, or it could be temporarily abandoned after the cementing just discussed has been completed. In the latter instance, the landing sub 16 is rotated free of the hanger 18 threading at 44, 56 by rotating the casing riser 24 from the surface. The riser 24 and landing sub are then Withdrawn from the well leaving the casing hanger 18 upper end, located near the mud-line, as the uppermost extent of the casing string 14. The riser (not shown) of the outermost casing is disconnected a few feet above the mud line, withdrawn to the surface and a temporary abandonment cap installed on the well, for instance as shown in the above-mentioned Pitts et al. application.

When other operations, such as the drilling of nearby formation definition wells, have been conducted and reestablishing contact between the sea surface and the subsea temporarily abandoned well is to be undertaken, the temporary abandonment cap is removed and the outer casing riser lowered and reconnected. In the normal case personnel tying back into the well 10 could then expect to lower the pipe or riser 24 with the landing sub 16 of FIGURES l and 2 on its lower end and reestablish the threaded connectition at 44, 56. However, in certain instances, through accident, lack of sufiicient skill on the part of some operating personnel, imprecise control over raising and lowering equipment due to rough seas or the like, it is anticipated that threads 44 can become so damaged as seen at 78 in FIGURE 3 as to prevent successful rethreading of the sub 16 threads 56 with the threads 44. Accordingly, there is provided according to the present invention a stab-in tieback 16', identical in all material respects to the landing sub 16 but for being smooth and threadless at the location of the threads 56 on the sub 16 and by being provided with external circumferential, spiralled teeth 80 arranged on the sub 16' to engage with the casing hanger teeth 50 when the seal at 40, 60 has ben reestablished. The teeth 80 each comprise a generally radially projecting, upwardly facing upper surface 82 and a generally flaring, downwardly facing, upwardly enlarging side surface 84. The teeth 80 are preferably hardened similarly to the teeth 50 as described above. Using the tieback sub 16 to reestablish contact with the well casing hanger 18 involves securing the sub 16 to the lower end of the riser or pipe 24 and lowering it from the surface within the bore of the outermost casing riser (not shown), guiding the nose of the sub 16' into the bore 30 of the hanger 18 and continuing to lower, whereupon the ribs 55 elastically deflect as the teeth 80 engage and run rough shod over the teeth 50 until the sealed and reconnected condition depicted in FIGURE 3 is reached. At this point the weight of the riser 24 and sub 16' is supported by the teeth 50 and sealing surface 40. If further support is necessary, for instance where the weight of the riser 24 and sub 16 is great, further engageable cooperative support surfaces can be formed on the sub 16' and casing hanger 18, such as a radial enlargement at 76 engageable with the hanger 18 upper end. Actually, abutment of the surfaces 40, 60 may provide a sulficient stop in most instances.

By virtue of the interlocking of the teeth 50, 80 and in particular the surface to surface abutment of the teeth surfaces 52, 82 an upward pull on the sub 16' will not tend to expand the ribs 55 or allow disengagement or withdrawal of the sub 16' from the hanger 18. However, because the teeth 50, 80 are in the nature of buttress threads or the like, disengagement can be effected if ever desired, by rotating the riser 24, and thus the sub 16', with respect to the hanger 18 in the sense to back the teeth 80 along the teeth 50 in an unthreading manner.

Accordingly, it should be apparent that the sub 16' can be stabbed-in without rotation, and rotated out if it is ever necessary to disengage it from the hanger 18.

As a nonlimitative example of apparatus according to the present invention, a coupling as described in regard to FIGURE 3 has been successfully established between a stabbed in tieback sub 16' and a hanger 16 where the hanger had an CD. of 8% inches, and 12 slits 32 each 8 inches long and 75 inch wide wherein the teeth 50, 80 were 2 threads per inch, 7%, CD. of sawtooth or ratched type threads having a total axial length of approximately 4 inches and a Rockwell C hardness of about 65 (flame hardened). The sub 16 and hanger 18 were composed of AISI 4140 steel and AISI 4140 steel, respectively, the ribs 55 were elastically deflectable at least A inch at their longitudinal midpoints.

It should now be apparent that the apparatus described herein well illustrates the principles of the present invention and that the embodiment depicted accomplishes each of the objects set forth hereinabove.

What is claimed is:

1. Well completion apparatus comprising: a tieback sub constructed and arranged for nonrotative stabbing into the bore of a remote tubular part for establishing connection therewith, said sub including a generally tubular body, securement means on the upper end of said body for attaching the sub to lowering means, and means for engaging and locking with the tubular part comprising a plurality of vertically adjacent circumferentially extending teeth on the exterior of said body intermediate the ends thereof, each tooth including a generally radially extending, upwardly facing circumferential upper surface and a generally outwardly and downwardly facing flaring circumferential side surface subjacent said upper surface; and the tubular part further comprising an integral, generally tubular collar body with a longitudinal throughbore, means defining a plurality of vertically elongated, angularly spaced narrow slits through said collar body terminating short of at least one end of said collar body and communicating with said throughbore, thereby defining ribs in said collar body between adjacent of said slits; a plurality of vertically adjacent circumferentially extending teeth internally of the collar body on said ribs; each tooth including a generally radially extending, downwardly facing, interrupted circumferential lower surface and a generally inwardly and upwardly facing, flaring, interrupted circumferential side surface suprajacent said lower surface, said teeth on said collar body being complementary to and interdigitable with the teeth on the tubular body of said sub; and said ribs being elastically deflectable, said sub thereby being nonrotatively insertable into the throughbore of the collar body sufiiciently to interdigitate said teeth on said collar body and said teeth on the tubular body of said sub; said tubular collar body extending substantially below the teeth thereon; said tubular collar body having means defining helical threading in the throughbore thereof below said teeth, constructed and arranged for rotative engagement with a correspondingly threaded element.

2. The well completion apparatus of claim 1 wherein the exterior of said sub body is generally cylindrically curved below said spiral threading leading to a lowermost nose defined on said sub, said nose having means defining an outwardly and downwardly facing generally frustoconically curved sealing surface thereon and means defining a circumferential radially outwardly opening groove in said sealing surface, said groove being constructed and arranged to receive a ring of packing material.

3. The well completion apparatus of claim 1 wherein the teeth on said collar body and the teeth on the tubular body of said sub comprise spiral threading, said sub being thereby rotatably disengageable from said collar body.

4. The well completion apparatus of claim 1 wherein the teeth on said collar body are substantially harder than the bulk of said ribs.

5. Well completion apparatus comprising: a tieback sub constructed and arranged for nonrotative stabbing into the bore of a remote tubular part for establishing connection therewith; said sub including a generally tubular body securement means on the upper end of said body for-attaching the sub to lowering means; and means for engaging and locking with the tubular part comprising a plurality of vertically adjacent circumferentially extend ing teeth on the exterior of said body intermediate the ends thereof, each tooth including a generally radially extending, upwardly facing circumferential upper surface and a generally outwardly and downwardly facing flaring circumferential side surface subjacent said upper surface; and further comprising a casing hanger constructed and arranged to dependingly support a string of casing and to be supported in a well, said casing hanger having: an integral generally tubular collar body with a longitudinal throughbore; means defining a plurality of vertically elongated, angularly spaced narrow slits through said casing hanger body terminating short of at least one end of said casing hanger body and communicating with said throughbore; thereby defining ribs in said casing hanger body between adjacent of said slits; a plurality of vertically adjacent circumferentially extending teeth internally of the casing hanger body on said ribs; each tooth including a generally radially extending downwardly facing, interrupted circumferential lower surface and a generally inwardly and upwardly facing, flaring, interrupted circumferential side surface suprajacent said lower surface, said teeth on said casing hanger body being complementary to and interdigitable with the teeth on the tubular body of said sub; and said ribs being elastically deflectable, said sub thereby being nonrotativel insertable into the throughbore of the casing hanger body sufficiently to interdigitate said teeth on said casing hanger body and said teeth on the tubular body of said sub; said casing hanger extending substantially below the teeth on said casing hanger body thereof; said casing hanger having means defining helical threading in the throughbore thereof below said teeth, constructed and arranged for rotative engagement with a correspondingly threaded element.

6. The well completion apparatus of claim 5 further including a plurality of radially directed, arcuately spaced circulation ports through said casing hanger body below said helical threading.

7. Well-completion apparatus comprising: a tieback sub constructed and arranged for nonrotative stabbing into the bore of a remote tubular part for establishing connection therewith, said sub including a generally tubular body, securement means on the upper end of said body for attaching the sub to lowering means, and means for engaging and locking with the tubular part comprising a plurality of vertically adjacent circumferentially extending teeth on the exterior of said body intermediate the ends thereof, each tooth including a generally radially extending, upwardly facing circumferential upper surface and a generally outwardly and downwardly facing flaring circumferential side surface subjacent said upper surface, and further comprising an integral generally tubular collar body with a longitudinal throughbore, means defining a plurality of vertically elongated, angularly spaced narrow slits through said collar body terminating short of at least one end of said collar body and communicating with said throughbore, thereby defining ribs in said collar body between adjacent of said slits, a plurality of vertically adjacent circumferentially extending teeth internally of the collar body on said ribs; each tooth including a generally radially extending, downwardly facing, interrupted circumferential lower surface and a generally inwardly and upwardly facing, flaring, interrupting circumferential side surface suprajacent said lower surface, said teeth on said collar body being complementary to and interdigitable with the teeth on the tubular body of said sub; said ribs being elastically deflectable, said sub thereby being nonrotatively insertable into the throughbore of the collar body sufliciently to interdigitate said teeth on said collar body and said teeth on the tubular body of said sub; and means defining cooperative circumferential sealing surfaces on said sub and said collar body engageable to limit axial penetration of the hub into the throughbore of said collar body.

'8. A conduit member constructed and arranged to dependingly support an exteriorly threaded other part, said conduit member having a generally vertically disposed tubular integral body with a longitudinal throughbore, said body having an upper end, means defining a plurality of vertically elongated, angularly, spaced narrow slits through said body terminating short of the upper end of said body and communicating with said throughbore, thereby defining ribs in said body between adjacent of said slits; a plurality of vertically adjacent circumferentially extending teeth internally of the body on said ribs; each tooth including a generally radially extending, downwardly facing, interrupted circumferentially lower surface and a generally inwardly and upwardly facing, flaring, interrupted circumferential side surface suprajacent said lower surface, said ribs being elastically deflectable for accommodating nonrotative insertion of the exteriorly threaded other part into said throughbore sufficiently to interdigitate the threads of said other part and the teeth on said ribs; said tubular integral body extending substantially below the teeth thereon; said tubular integral body having means defining helical threading in the throughbore thereof below said teeth, constructed and arranged for rotative engagement with a correspondingly threaded element.

References Cited UNITED STATES PATENTS 337,589 3/1886 Knapp 287-126 X Cox 285-34 Sheldon 285-390 Rader 285-302 Paulsen 85-33 X Baker 285-34 Baker 285-141 X Koppl 285-391 X Brown 285-142 X Roulins 285-34 X Gibbs et al. 285321 X Natho 285-3-323 X Assistant Examiner US. Cl. X.R. 

